HIV infection has been demonstrated to increase vulnerability to malaria infection and disease, but the mechanisms behind this observation are not understood. Current evidence suggests that increased malaria vulnerability among individuals with HIV infection may be due in part to a defect in the immune system's ability to create and maintain antibodies that target malaria. This evidence includes a robust body of literature supporting the critical role of antibodies in protection from malaria and an increasing understanding of how HIV infection affects the immune systems ability to mount effective antibody responses. Specific Aims: 1) Determine antibody reactivity of HIV-positive versus HIV-negative individuals to multiple malaria proteins; 2) Determine the frequency of different types of B-cells that specifically target malaria. B cells are the immune cells responsible for antibody production, and different types of B cells have differing abilities to produce effective antibody responses. Study Design: For this study, blood will be collected from HIV infected and uninfected persons living in a malaria endemic region in Kenya. Antibody responses that target malaria and B cell numbers and types that target malaria will be measured in these blood samples and these responses will be compared between HIV infected and uninfected study participants. Potential Impact: This project will for the first time characterize malaria-specific -cell responses in HIV-positive individuals. It will assist in determining if this population should receive targeted malaria interventions and will help devise evidence-based strategies for malaria vaccine design and HIV treatment for HIV-positive individuals.